During surgical operation, human skin (a natural barrier against microorganisms) is cut through at a predetermined operating site, and internal tissues which should be aseptic by nature are then exposed to the external environment. This greatly increases the risk of a surgical site infection (SSI). Therefore, the skin at and around the operating site must be disinfected to reduce the number of microorganisms existing there to the smallest possible number. Even after disinfection, the microorganisms remaining on the skin may cause an infection during the surgical operation. In order to minimize potential of infection, a sterilized surgical drape that is made of a transparent, thin adhesive film is generally used, which may be called as “surgical drape for incision” or “incise drape”. The incise drape is adhered and affixed onto the skin around the operating site prior to the operation, and allows the skin together with the drape to be incised by means of a surgical knife or the like, to aid in preventing any microorganism remaining on the skin at and around the incised site from invading inside of the body through the incised site. After a surgical operation, the wound is typically covered with a thin and flexible film, which may be called a “wound dressing”, in order to create an optimized environment for healing while obviating any infection from the external environment.
There are known dressing films and surgical drapes made with iodine-containing pressure sensitive adhesives for use in antimicrobial medical applications, as described in U.S. Pat. No. 4,310,509; U.S. Pat. No. 5,829,442 and the like. However, these pressure sensitive adhesives are dissolved or dispersed in an organic solvent such as toluene, methyl ethyl ketone or the like. Such a solvent-based pressure sensitive adhesive may have adverse affects on the human body and the environment, as well as having certain cost and process issues. Therefore, there is a need for an iodine-containing pressure sensitive adhesive that does not utilize organic solvents which may adversely affect the human body and/or the environment, and a process of making the same.
As iodine has a tendency to easily sublime as well as having a boiling point of 106° C., it is difficult to make a hot melt pressure adhesive containing iodine, and coat the adhesive using a typical hot melt coater of which coating temperature is over 110° C. In order to obtain a hot melt pressure adhesive capable of being coated by a typical hot melt coater (typically at a coating temperature of about 140 to 160° C.), a hot melt pressure adhesive composition has been developed, which comprises an antimicrobial agent diiodomethyl-p-tolylsulfone which is stable at a temperature of 275 to 350° F. (135 to 177° C.) so as to enable the adhesive composition to be coated using the hot melt coater. However, it has been found that this antimicrobial agent has a different antimicrobial spectrum and a poor antimicrobial efficacy, as compared to iodine (I2, or polyvinyl pyrrolidone-iodine complex (also referred to simply as “PVP-iodine complex”)).